A151746 G.f.: (1-2*x-5*x^2+4*x^3)/((1-4*x)*(1-x)^2).

1, 4, 10, 32, 118, 460, 1826, 7288, 29134, 116516, 466042, 1864144, 7456550, 29826172, 119304658, 477218600, 1908874366, 7635497428, 30541989674, 122167958656, 488671834582, 1954687338284, 7818749353090, 31274997412312, 125099989649198, 500399958596740

Offset: 0

Author

N. J. A. Sloane, Jun 16 2009

Keywords

• nonn

Crossrefs

Subsequence of A151735 at powers of 2.

Programs

Mathematica

CoefficientList[Series[(1-2x-5x^2+4x^3)/((1-4x)(1-x)^2),{x,0,30}],x] (* Harvey P. Dale, Jan 13 2015 *)

Formula

a(n) = 14/9+2*n/3+4^(n+1)/9, n>0. [From R. J. Mathar, Jun 17 2009]